Health literacy is the ability to understand, communicate, and use information in health care. Low health literacy (HL) affects use, quality, outcomes, and costs of medical care for 25-50 percent of US adults. Knowledge Gaps: Little is known about HL among youth. Health literacy may be particularly important for 17-25 year-olds who must assume responsibility for their own health care decisions in the transition from pediatric to adult health care. New information is needed about HL measurement as a precursor to future studies of HL and health care transition, yet few HL measures have been tested in this age group. Objectives: Objective 1: Evaluate strengths and limitations of five validated HL tools for use among 17-25 year-old transition-age youth, {and asses youth opinions about HL and the measurement tools. Objective 2: Measure basic health skills among youth, associations with HL scores, and assess youth opinions about health skills, health care challenges, and transition.} Objective 3: Conduct focus groups to more deeply explore youth perspectives and elicit youth suggestions and opinions about future interventions among adolescents and young adults. {Methods: Sample 280 17-25 year-olds from health care and education settings in Monroe County, New York. Aim 1a: Administer five HL tools that were validated in other age groups and determine the psychometric properties of each instrument. Aim 1b: obtain participant feedback about the tools and perspectives on HL. Aim 1c: identify strengths and limits of each tool based on: psychometric properties, validation against a standard for reading literacy, ease of use, administration time, and participant preferences. Aim 2a: Measure participant competence in performing basic health tasks (e.g. medication use) and correlate youth competence in health skills with youth HL scores. Aim 2b: Assess youth perceptions and opinions about health skills, health care, and transitions via semi-structured and open-ended questions. Aim 3: Conduct focus groups to explore in more depth the key constructs from Aims 1b and 2b, using HL results and health skills competence (along with age and gender) to help select and group participants for focus group discussions.} Project Team: Includes a new investigator and national leaders in health literacy and functional health skills measurement, psychometrics, adolescent health care transitions, and health services research. Significance: Identification of tools and methods that can effectively measure health literacy among 17-25 year-old youth is a necessary first step in further study of health literacy in this previously unexplored age group. Results will be used in subsequent studies to: 1) estimate the prevalence of health literacy problems among youth;2) examine associations between health literacy and youth health care skills, health care experiences, outcomes, and costs;and 3) develop interventions to improve those outcomes among transition- age youth and improve their ability to function effectively as adult consumers of health care. Public Health Relevance: It is important to identify low HL among 17-25 year-old transition-age youth in order to design and implement services to facilitate the transition from pediatric to adult care and improve health literacy among youth.